This invention relates to a portable apparatus for reading an optical code. The term "optical code" is used here to designate an aggregate of graphic markings (either applied on a label or directly on a product) which are used to encode information in the form of sequentially arranged black zones and white zones, or variously colored zones, lying along the same or different directions. Examples of such codes are the bar codes, two-dimensional codes, color codes, etc.
Optical codes can be read using stationary or portable reading apparatus. Portable readers have an outer case formed with a reading window through which both a means of illuminating a code to be read, and a means of reading a light image of the illuminated code by detection of the light scattered therefrom and conversion of same to electrical signals, are active. The light-sensitive elements which effect the conversion of the light signal to an electric signal can be of various types; in general, a so-called CCD (Charge Coupled Device) is used which includes a matrix comprised of a very large number of individual light-sensitive elements.
A major problem to be solved in portable optical code readers is to avoid that the light issuing from the illumination means may become mixed up with the light scattered back from the code, and thus reach the light-sensitive element to make a correct reading of the code impossible to obtain.
A document U.S. Pat. No. 5,484,994 teaches that the light issuing from the illumination means can be confined within obscure chambers open to the reading window, these obscure chambers being fully isolated from another obscure chamber which encloses the optical detection path travelled by the light image from the illuminated code.
Widely in use are portable readers of angled design, wherein the light image from the illuminated code is to travel an angled path before eventually striking the light-sensitive element. This deflection, being an obtuse angle in the 110.degree. to 160.degree.0 range, is provided by a plane mirror or some other suitable reflective element.
In this case, the problem of avoiding that the light from the illumination means may get mixed up with the light image from the code, actually becomes one of preventing the illuminating light from reaching the mirror directly.